The paper finds imbalance of sex ratio at birth and analyzes some possible determinants on
sex ratio at birth in Viet Nam by using the Vietnam Population Census 2009. This paper
concentrates to analyze the parental interference of child sex. Although the magnitude of
correlation between the parental characteristics and the gender of children is not high, this
correlation is statistically significant. The result of this paper concludes that gender of the
firstborn, birth order, ethnicity of parents, the age of parents as well as their education level
are associated with the sex of children. More specifically, having the firstborn boy reduces
the probability of having boys in the next birth. Children with higher birth order are more
likely to be male. It implies that parents follow male-preferring stopping rule. Several
households are more likely to have children until they get a boy. Kinh parents with higher
education are more likely to have boys than ethnic minority parents with lower education.